body {
    background: #f0f2f5;
    display: flex;
    justify-content: center;
    align-items: flex-start;
    min-height: 100vh;
    padding: 3rem 1rem;
    font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
}

.panel {
    background: #fff;
    padding: 2.5rem 2rem;
    border-radius: 1rem;
    box-shadow: 0 0 30px rgb(0 0 0 / 0.1);
    max-width: 480px;
    width: 100%;
    text-align: center;
}

h3 {
    margin-bottom: 2rem;
    font-weight: 600;
    color: #333;
}

.btn-group {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    justify-content: center;
}

button,
a.btn {
    flex: 1 1 45%;
    min-width: 140px;
    padding: 0.6rem 1rem;
    font-weight: 500;
    transition: background-color 0.2s ease;
}

.output {
    margin-top: 1.5rem;
    padding: 1rem;
    background: #f7f9fc;
    border-radius: 0.5rem;
    font-family: monospace;
    white-space: pre-wrap;
    min-height: 4rem;
    color: #444;
    user-select: text;
    box-shadow: inset 0 0 5px rgb(0 0 0 / 0.05);
}

.loading {
    opacity: 0.7;
    pointer-events: none;
}